Synthesis of uniform nickel oxide nanoparticles embedded in porous hard carbon spheres and their application in high performance Li-ion battery anode materials

Abstract

Uniform nickel oxide nanoparticles (~10 nm) embedded in porous hard carbon (HC) spheres (90- 130 nm) for high performance lithium ion battery anode materials were synthesized via a hydrothermal method followed by impregnation and calcination. The HC spheres, which had abundant micropores and plentiful surface functional groups, allowed firm embedding and uniform dispersion of the NiO nanoparticles. The as-prepared HC/NiO composite anode exhibited excellent electrochemical performance, including high reversible capacity (764 mAh∙g-1), good cycling stability (a high specific capacity of 777 mAh∙g-1after the 100th cycle at a current density of 100 mA∙g-1, a capacity retention rate of 101%), and high rate capability (380 mAh∙g-1even at 800 mA∙g-1). These excellent electrochemical properties were attributed to the unique structure of NiO nanoparticles tightly embedded in a hard carbon matrix. Anode materials with such a structure have the advantages of improved electronic conductivity, more accessible active sites for lithium ion insertion, and short diffusion paths for lithium ions and electrons. The observed“synergistic effects”between the hard carbon and NiO represent an advance in the electrochemical performance of such composites. The present method is an attractive route for preparing other hard carbon/metal oxide composite anodes for lithium ion batteries.